US2935938A - Methods of copy reproduction - Google Patents

Description

United States Patent 2,935,938 lVlETHODS OF COPY REPRODUCTION Denis Joseph OSnllivan, Essex, England, assignor of one-' half to Eugene Lefebure, Eniield, England No Drawing. Application April'17, 1956 Serial No. 578,594

3 Claims. c'l. 101-149.4

This invention deals wth improved methodsof producing copies by typewriting, handwriting or printing and with meansof reproducing copies from anoriginal; it relates in particular to hectographic reproducing processes.

of the spirit-reproductionprocess in which, instead of using a dyestuff in the formulation of the transfer coating on the base sheet, a dye intermediate is used which, when brought into contact with copy paper damped with a liquid containing a coupling agent, will combine to form the dye. This process has a great advantage in that the transfer sheet is perfectly clean to handle. A disadvantage is that the dye intermediates'disclosed are in general of the azo type and consequently are much less brilliant and do not produce as many copies in the finished state as the triphenylmethane dyes.

It is an object of the present invention to provide a method of producing copy on paper employing an improved form of transfer paper which obviates the above disadvantage.

We have now found it possible to produce an improved It has previously been proposed to use a variation transfer paper having as the transfer coating colour-re active complexes formed by a combination of certain dyes or reduced dyes or dye intermediates with higher alkylamines. These novel colour reactive complexes are far more stable than previously known non-staining materials and can be oxidised by the use of mild reagents. Such reagents include derivatives of succinic acid ,and hydroquinone with high oxidation potentials.

These new colour-reactive complexes are not liable to oxidise under normal atmospheric conditions or under light and heat.

Accordingto the present invention there is provided a method of producing copy on paper which method comprises bringing into superimposed relationship a sheet of paper having impressionsthereon of acomposition .consisting of or comprising a colourless or .substantially colourless complex formed by the combination of a dye, reduced dye or dye intermediate with a non-ionising saltfree surface active agent and a second sheet of paper coated with or having incorporated therein an oxidising agent capable of reacting with the aforesaid complex to produce a colour product, and thereafter applying pressure to the superimposed sheets to develop a coloration on the sheet containnig or coated with the oxidising agent at those points corresponding with the impressions .on the complex-coated sheet.

By the expression non-ionising salt-free'surface active agent as used herein we mean a surface active agent which does not dissociate to yield a free acid radical.

When the present invention is to be applied to the hectographic reproduction process the colour reactive complex is incorporated with suitable waxes and/ or waxlike materials to formthe transfer coating of the 1mcoloured carbon paper and when the master copy is typed a mirror image impression is obtained, which is'substantially non-staining. The oxidising agent is incorporated "ice in the liquid used in the reproduction process. When solid oxidising agents dissolved in the liquid are used it is advisable to employ spirit-reproducng machines which deliver the liquid by means of pumps or gravity feed, and apply the liquid to the copy paper by means of damping rollers to which the liquid is fed by a system of intermediate rollers or sprays. .When liquid oxidising agents are used it is possible to employ the older types of spiritprocess machines depending on the delivery of the liquid to the paper by capillary action through pads or Wicks.

Dyes suitable for use in connection with the invention are the triphenylmethane and diphenylnaphthylmethane dyes, e.g. Crystal Violet, Victoria Blue and Malachite Green, in their leuco base form. Since these dyes exist in several forms other than the leuco base, the following structural formulae, using Malachite Green as an example, will serve to distinguish these forms and to clarify the nature of the dye material from which the stable complex is prepared:

(a) The dyestuff or dyesalt itself (a hydrochloride):

(b) The dye base or carbinol form: I

(c) The sodium salt of the dyebase (color base) or carbinol form I @mcrpp .(d) The leuco base:

Where the, term leuco is used herein, the last of these forms is intended.

According to the present invention, the leuco base form of the particular dyestuif is reacted with a higher alkylamine to form a stable color-reactive complex. As a preliminary step, the leuco form may be reacted with a strongly basic compound such as primary amine or an alkali metal or alkaline-earth metal base to produce a dye intermediate, after which the complexing reaction with the higher'alkyl amine is carried out. The structure of the alkaline salt of the leuco base form is extremely diflicult to establish and it is not possible herein to illus rial that is particularly adapted for use in a transfer coating in connection with hectographic reproduction processes.

One preferred form of the dye intermediate is the amino salt of the leuco dye obtained by reacting the leuco dye with a strongly basic primary amine for example a diamine such as stearyl'diarnine or l-auryl diamine. Thus the leuco compound may be dispersed in water at to 3 100 C. and stearyl diamine added with stirring when reaction takes place to give astable salt. This salt may also be prepared in the oil/wax vehicle of a normal hectographic coating composition.

Alternatively the dye intermediate is that obtained by reacting the leuco compound with an alkali metal or alkaline-earth metal'base to form the alkali metal or alkaline earth metal leuco form of the dye. Thus the leuco compound may be reacted with a strong base such as sodium hydroxide thereby forming the sodium leuco form of the dye. The strong base may be dissolved in the least possible quantity of water and added to a boiling solution of the leuco form of the dye in dioxane, an offwhite product being obtained which is stable in air and light up to a temperature of 70 C. The sodium leuco form of the dye may also be prepared by boiling the leuco in a concentrated aqueous solution of caustic soda.

The complex formation is carried out byheating the dry components together, at a temperature of approximately 90 C. in the case of the amino-leuco salt, with stearylamine and, at a temperature of about 100 ,C. in the case of the alkali-metal or alkaline earth metal base salt, with stearylamine or alternatively in the oil/wax hectographic coating composition.

Suitable non-ionising salt-free surface active agents are higher alkylamines such as stearylamine.

Examples of suitable oxidising agents include derivatives of quinone e.g. tetrachloroquinone and derivatives of succinic acid e.g. N-bromosuccinimide.

In an alternative form of the present invention the oxidising agent comprises a two component system, one

' component being combined in the transfer coating and the other incorporated in the liquid with which the copy sheet is wetted. Some of these oxidation systems are purely organic in nature, some are inorganic while the preferred are a combination of both.

Examples of such systems are:

(a) Potassium permanganate in the coating with chloranil contained in a liquid comprising a ketone and a chlorinated solvent.

(b) Potassium permanganate combined in the coating with chloranil contained in liquid comprising a ketone and nitrobenzene.

Potassium permanganate combined in the coating with N-bromosuccinimide in a liquid comprising a ketone and a chlorinated solvent.

(d) Potassium permanganate combined in the coating with chloranil contained in a liquid comprising a ketone and a 0.5% surface active quaternary ammonium compound.

The transfer coatings which incorporate the colourreactive complexes (other than those including inorganic oxidising agents) are almost white or 'are very pale, depending to a large extent on the colour of the waxes or wax-like materials used in their composition. It may be found useful to incorporate in the complex-coating a small proportion of a corresponding partially reacted and therefore faintly coloured complex sufficient to give a slight indicative colour to the coating without causing any stain. This procedure has the advantage that a transfer -paper with such slightly coloured coating denotes the overlying protective coating or the use of any other pro tective measures within the transfer coating or base paper. Such a super-coating may, however, be applied to the complex coating, if desired, e g. to indicate the colour of the reproductions obtainable from the transfer paper. In this case it will be found useful to incorporate into the supercoating a coloured impalpable fine grade of aluminum powder in the desired colour. The addition of this aluminium powder has also the advantage that it makes the super-coating more friable, and this effect can be improved by adding other impalpable fillers such as china clay, asbestos powder, mica powder, talcum or silica gel. In one form of the invention the oxidising material may be incorporated in the copy paper by mixing in the pulp. V

The complexes of the present invention are substantially water insoluble and may be used in hydrophilic coatings. For example, the transfer coating may consist of a dispersion of colour reactive material dispersed in film forming hydrophilic materials such as starch, casein, gelatine or synthetic polymeric materials such as methyl cellulose. Inert fillers such as china clay and alumina may also be incorporated both to assist transfer and intermingling of the coatings when copy is being produced. I

Following is a description by way of example of methods of carrying the present invention into effect in a hectographic spirit duplicating process.

Example I Eight to ten parts by weight of amino leuco crystal violet salt such as the stearyldiamine, phenylenediamine, diphenylamine, diethanolamine, ethylene diamine or spermine salts are reacted with one part of stearylamine at C. until the reaction is complete giving a white product. The complex is then incorporated with wax and filler to form a normal hectographic coating. This is applied to the transfer sheet.

Example I! Example III Equivalent proportions of leuco crystal violet and a C alkylamine are reacted together at C. until the mixture changes colour. The complex is incorporated with wax and filler to form a normal hectographic transfer coating composition. This is applied tothe transfer sheet.

Example IV In this example the leuco crystal violet and the alkylamine are heated together in the presence of the principal wax constituent or constituents e.g. carnauba wax or microcry'stalline wax to form the basis of the hectographic transfer coating composition.

Example V Eight parts by weight of an alkaline metal leuco crystal violet salt such as the sodium, potassium or barium salt, are reacted with one part of stearylamine at 80 C. until the reaction is complete giving a white product. The complex is then incorporated with wax and filler and inorganic oxidising agent such as potassium permanganate to fo'rm anormal hectographic coating.

Example VI In this example the alkaline metal leuco crystal violet salt and the stearylamine of Example V are heated together in the presence of the principal wax constituent or constituents, e.g. carnauba wax or microcrystalline wax tovforrn the basis of the hectographic transfer coating somp it A master is made from the transferisheets of any one of the specific examples and copy obtained from this master by a hectographic reproducing process in which the copy paper is damped with a liquid of which the following are examples:

Percent A Methylethylketone 99 Chloranil 1 B Methylethylketone 90 Tetrachloroethylene 9.5 Chloranil 0.5

, C Methylethylketone 80 Tetrachloroethylene 9.5 Dioxane v Chloranil 0.5

' v D Methylethylketone 90 Perchlorethylene 9.5 N-bromosuccinimide 0.5 E Acetone 80 Dioxane 10 Trichlorethylene 9.5 Chloranil 0.5

, F Methylethylketone 90 Tetrachlorethylene 9 p-Nitropbenyl iso-cyanate 0.5 Chloranil 0.5

G Methylethylketone 99 Chloranil 0.5 p-Nitrophenyl iso-cyanate 0.5

The transfer sheet is produced by any of the conventional coating procedures, viz. roller coating (with or without doctor blades), fountain coating or spray coating. The coating is applied either as a hot melt mix at a temperature of the order of 130 C. or in the form of a true or colloidal solution with a suitable solvent at a temperature of the order of 50 C. Suitable solvents include petroleum distillates, esters and ketones admixed with the solids in the proportion of 1 of solids to 1 of solvents by weight. The solvents are completely removed by evaporation over hot rollers or in drying tunnels subsequent to the coating operation. When usinga solution it is desirable to 'use a body paper which is very hard 6 I. claim: i

, 1. A method of producing copy by a hectographic reproducing process comprising imaging a master sheet from a transfer sheet having a transfer coating consisting essentially of wax in admixture with a substantially colorless complex formed by the combination of (a) the leuco form of a dye selected from the group consisting of a triphenylmethane dye and a diphenylnapthyl methane dye with (b) a non-ionisingsurface active agent consisting of a higher alkylamine, and transfering some of the complex -to a copy sheet brought into superimposed contacting relationship with the master sheet, the coloration being developed by oxidation of the complex by means of an oxidizing agent therefor present on the surface of said copy sheet.

2. A method of producing copy by a hectographic reproducing process comprising imaging a master sheet from a transfer sheet having a transfer coating consisting essentially of wax in admixture with a substantially colorless complex formed by the combination of (a) the salt of a strong base selected from the group consisting of the primary amines, alkali metal bases, and alkaline-earth metal base with the'leuco form of a dye selected from the group consisting of a triphenylmethane dye and a diphenylnaphthylmethane dye with (b) a non-ionising surface active agent consisting of a higher alkylamine, Wetting the surface of a copy sheet with a liquid containing a compound selected from the group consisting of tetra chloroquinone and N-bromo-succinimide, and contacting the wetted copy sheet with the imaged surface of the master sheet in order to effect transfer of some of the complex to the copy sheet to develop a coloration on the copy sheet to develop to the imaged master.

3. A transfer sheet for use in a hectographic reproducing process which sheet comprises a base sheet having a transfer coating thereon consisting essentially of wax in admixture with a substantially colorless complex formed by the combination of (a) the leuco form of a dye selected from the group consisting of a triphenylmethane dye and a diphenylnaphthylmethane dye with (b) a non-ionising surface active agent consisting of a higher alkylamine.

or alternatively, is sized, waxed, printed or treated with References Cited in the file of this patent UNITED STATES PATENTS 2,040,075 Brower May 12, 1936 2,077,874 Brower Apr. 20, 1937 2,554,909 Holik May 29, 1951 2,634,677 Klimkoski et al. Apr. 14, 1953 2,755,200 Balon et al July 17, 1956 2,755,201 Webber et al. July 17, 1956 2,755,202 Balon et al. July 17, 1956 2,755,203 Statlman July 17, 1956

Claims (1)

1. A METHOD OF PRODUCING COPY BY A HECTOGRAPHIC REPRODUCING PROCESS COMPRISING IMAGING A MASTER SHEET FROM A TRANSFER SHEET HAVING A TRANSFER COATING CONSISTING ESSENTIALLY OF WAX IN ADMIXTURE WITH A SUBSTANTIALLY COLORLESS COMPLEX FORMED BY THE COMBINATION OF (A) THE LEUCO FORM OF A DYE SELECTED FROM THE GROUP CONSISTING OF A TRIPENYLMETHANE DYE AND A DIPHENYLNAPHTHYL METHANE DYE WITH (B) A NON-IONISING SURFACE ACTIVE AGENT CONSISTING OF A HIGHER ALKYLAMINE, AND TRANSFERING SOME OF THE COMPLEX TO A COPY SHEET BROUGHT INTO SUPERIMPOSED CONTACTING RELACTIONSHIP WITH THE MASTER SHEET, THE COLORATION BEING DEVELOPED BY OXIDATION OF THE COMPLEX BY MEANS OF AN OXIDIZING AGENT THEREFOR PRESENT ON THE SURFACE OF SAID COPY SHEET.